Effects of Ultrasonic Transducer in contact with glass

[Mark Brown]

I'm looking for a way of using ultrasonic cleaning to clean the inside of a glass vessel filled with some sort of fluid by transmitting ultrasounds through the glass, rather than submerging the entire glass vessel. If an ultrasonic transducer, let's say something with a maximum frequency of 40 kHz, was in direct contact with a glass surface, would it shatter the glass surface? If so, are there ways of using some sort of ultrasonic destructive interference, or any other methods, for mitigating energy transfer to the glass but still providing cavitation of the fluid inside the vessel? Thanks in advance for your insight

 

[nasu]

The effect will depend on the power transmitted to the glass. If the power is low enough of course it will not shatter the glass.
The ultrasound by itself does not have any special destructive power. It is like any other sound. If the frequency of the transducer happens to be close to some resonance frequency of the vessel then you will transmit more power to the glass and the effect is enhanced. Same as for audible frequencies.
I would just start with a low power and increase it gradually. But it depends a lot on your setup.

 

[sophiecentaur]

Could you use a suitable Gel to get good coupling to the glass? It would avoid high stress at local points of contact and you would get better power transfer.
Obvs you have to start off at low power and give it time to work, rather than being impatient and turning up the wick to soon!
Do you have a spare replacement glass vessel?

 

[Nik_2213]

During a long, unattended run in our big sonic baths, water would evaporate until there was only an inch or two, so part-filled flasks stood on the bottom, just above the transducer. They often rattled about, but we never had one break. Of course, the power available was limited to flask-safe. Industrial-rated transducers, for 'process' work, may be harsher...

Um, medical ultrasound scans and industrial crack-hunting seem to use a gel to enhance energy transfer...

I've seen 'immersion' transducers, which may be dipped into fluid like a 'tropical' aquarium or 'home-brew' heater. Would one of those solve your coupling problem ??
==

FWIW, I remember our manager wandering through at lunch-time, glancing into the sonic baths and doing a splendid double-take.
"What's THAT ??"
"Motor-bike engine."
"Huh ?"
"Pete's changing the leaky head-gasket. Should be a half-hour job, but some of the old sealant baked on. If he can't shift it, he'll have to leave real-early to catch his bus/train/bus connections. Which means that urgent batch won't get run tonight."
"Oh... Well, I hope it works out !"
It did.
;-)